Issue of the Week: Defining Natural Diversity

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“Natural diversity” is a common term used in science that generally refers to the variety of plants and animals found in a particular place or ecosystem. The term biodiversity is often used interchangeably with natural diversity. It can also mean the variation within a given species, referring to the species’ genetic makeup.  These are easily understood concepts that biologist and naturalist have been using to describe life on earth since Charles Darwin’s famous novel, On the Origin of Species by Means of Natural Selection.

However, the U.S. Fish and Wildlife Service (USFWS) uses the term “natural diversity” to mean something more specific. They define it as “the number and relative abundance of indigenous species which would occur without human interference.” (Link) While the number and relative abundance of species can be easily quantified; modifying that statement with “which would occur without human interference” is alarming. Humans use these environments and should be considered in making management decisions.  Generally, the USFWS uses this term when discussing the requirements for National Wildlife Refuges, which sometimes leads to issues in a state’s ability to manage its wildlife effectively.

Here lies a problem. Relative abundance of a species is difficult enough to scientifically estimate, let alone the relative abundance which would occur without human interference. This is especially difficult since the USFWS has not provided clear and quantifiable metrics to systematically determine what the “natural diversity” of an area includes. And how does one measure the impact of human interference without introducing many assumptions of what would be natural?

It is nearly impossible to decide what would occur without human interference, especially since humans are allowed to use so many of these areas. The National Refuge System was designed to conserve wildlife and their habitats, but they also provide opportunities for hunting, fishing, wildlife observing and photography, and environmental education. All of these purposes are outlined as appropriate uses of refuges.

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Problems with the buzzword have appeared in Alaska. Federal wildlife refuges in Alaska are mandated to conserve species and habitats in their “natural diversity” and ensure that the biological integrity, diversity, and environmental health of the refuge system are maintained for future generations. This means that on refuge lands the USFWS deems what types of management are appropriate or needed to comply with their mandate.  This has conflicted with how the Alaska Department of Fish and Game prefers to manage certain species, such as moose and wolves.

What is the natural number of wolves and moose, and what would that number be if humans were not managing or harvesting either of them?

Another major concern is a scenario where the federal government insists on managing for natural diversity on all federal lands. This could mean that the take and use of resources on BLM, Forest Service and Wildlife Refuges could be strongly restricted in order to preserve the biodiversity that would be naturally present without human intervention. Well, in the absence of sustainable use and wildlife management, populations of plants, herbivores and predators will boom and bust on their own. This has been shown over and over again in wildlife science, and likely not the desired outcome.

Absent the metrics to determine “natural diversity” decision-making criteria by the USFWS becomes broader, making it much easier for the refuge manager to justify closures or prohibit the approved public uses. They can also interfere with the states’ ability to effectively and safely manage wildlife. The USFWS is considering amending regulations governing Alaska refuges to ensure that they are managing those refuges in accordance with the mandates. Hopefully, these proposed changes will include better and more defined criteria for their definition of “natural diversity.”

Twice a week, SCI Foundation informs readers about conservation initiatives happening worldwide and updates them on SCI Foundation’s news, projects and events. Tuesdays are dedicated to an Issue of the Week and Thursday’s Weekly Updates will provide an inside look into research and our other science-based conservation efforts. Follow us on Facebook and Twitter for more SCI Foundation news.

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